Hi, You're here because your project has issues related to Xcode Previews or Swift Previews. The issue you're experiencing may be the result of any of the following: An error in your SwiftUI app, Xcode previews, or on-device previews. A configuration error in your Xcode project, including any third-party dependencies or packages. A system issue in the operating system, SwiftUI, or in Xcode Previews. Based on your request, I need more information about your SwiftUI app when rendering Xcode Previews or on-device previews. Specifically, I’ll need the diagnostics Swift Previews generates to make sure I understand the error encountered by the preview system. Please create a report in Feedback Assistant to share the details requested in the instructions below. For issues with macOS, Mac Catalyst, on-device iOS, or on-device visionOS previews, perform the following steps to gather diagnostics: Download and install the Swift Previews logging profile for your device. Reproduce the error while previewing on device, taking note of the timestamp when the error occurred. Attach the Previews diagnostics, sysdiagnose from your Mac, a sysdiagnose from the previewing iOS or visionOS device. For issues with Xcode Previews, perform the following steps to gather diagnostics: Download and install the Swift Previews logging profile for your device. Reproduce the error in Xcode Previews, if you haven’t already done so. If an error banner appears in the canvas, click the "Diagnostics" button within the banner, then go to Step 5; otherwise, continue to Step 4. If the error banner is missing, navigate to the menu in Xcode: Editor > Canvas > Diagnostics In the presented sheet, click the "Generate Report" button. Attach a zip file containing the diagnostic report to your bug report (it will be named something like previews-diagnostics-0123456789.zip). Submitting your feedback Before you submit to Feedback Assistant, please confirm the following information is included in your feedback: with the Swift Previews logging profile installed, attach the sysdiagnose logs gathered after reproducing the issue the Previews diagnostics generated by Xcode timestamp identifying when the issue was reproduced focused sample Xcode project that reproduces the issue (if applicable) screenshots or videos of the error (optional) Please include all requested information to prevent delays in my investigation. After your submission to Feedback Assistant is complete, please respond to your original Forums post with the Feedback ID. Once received, I can begin my investigation and determine if this issue is caused by an error within your SwiftUI app, a configuration issue within your Xcode project, or an underlying issue in the operating system, SwiftUI, in Xcode Previews, or on-device previews. Cheers, Paris X Pinkney |  WWDR | DTS Engineer

I am experiencing an issue where my Mac's speakers will crackle and pop when running an app on the Simulator or even when previewing SwiftUI with Live Preview. I am using a 16" MacBook Pro (i9) and I'm running Xcode 12.2 on Big Sur (11.0.1). Killing coreaudiod temporarily fixes the problem however this is not much of a solution. Is anyone else having this problem?

Is there any way to stop previews from live updating? It's constantly running and that's nice when I'm developing, but I'd like it to pause updating when I'm not using the Xcode. It heats up my m1 air and drains unnecessary power reducing the battery levels significantly.

Greetings... I am trying to use @Namespace for my matchedGeometryEffect use case. prior to Xcode 15 beta the following code worked just fine: struct ChapterItem_Previews: PreviewProvider { @Namespace static var namespace static var previews: some View { ChapterItem(namespace: namespace, show: .constant(true)) } } However trying to do the same within the new Xcode 15 beta #Preview Macro #Preview { @Namespace var namespace ChapterItem(namespace: namespace, show: .constant(true)) } produces the following error message: Ambiguous use of 'Preview(_:traits:body:)' May I kindly get assistance on the proper way I can get this to work in Xcode 15 beta? Please be as detail as you can since I'm still new to swiftUI as well Thank You.

Hiya, I am having issues trying to use previews in the xcode 15 beta, i am using an M2 macbook air with 8gb of ram. I am using MacOS Sonoma and iOS 17.0 Beta 1 and am struggling using previews, the base simulator works but no previews. I am not receiving any error so am very confused. Any help would be majorly appreciated. Thanks, Gus

SwiftUI preview hangs on "Preparing iPhone Simulator for Previews". Also simulator hangs when trying to build and run. This occurred after I installed iOS 17 simulator. I tried reverting back to an iOS 16 version of the simulator, but haven't figured out how to do that. Build and run to an iPhone device works fine. Any ideas would be appreciated. Thanks.

Cannot select individual view in selectable mode in Xcode preview, it only show the whole blue device border.

When I attempt to preview my code, I encounter an error message stating, “Cannot preview in this file: Failed to launch (App Name).” This issue is specific to this particular app. I attempted creating a new project, and that works fine. This is what it says in the diagnostics: | [Remote] JITError | | ================================== | | | [Remote] LLVMError | | | | LLVMError: LLVMError(description: "The file was not recognized as a valid object file")

Up until now, it was possible to check in build scripts via the ENABLE_PREVIEWS environment variable whether a build for a SwiftUI preview is being executed. In addition, it was also possible to conditionally compile code for SwiftUI or exclude it from compilation using this variable. This no longer works with Xcode 16 and the new SwiftUI Preview compilation! There is still the option to switch to the old system with the "Use Legacy Previews Execution" setting, but as stated in the release notes, this option will be removed at some point. Which brings us back to the old problem of not being able to exclude build scripts from preview builds and not being able to prevent certain code from being compiled / add special code for SwiftUI previews. This is a terrible situation, especially for more complex projects in which precisely the points mentioned are important for the build process. I seriously hope Apple provides us with another environment variable for SwiftUI preview builds that we can use.

I’ve noticed a strange bug in Xcode 16 and Swift. When a preview is rendering and hasn’t finished yet and you run an app to debug, Xcode is launching two instances of the app. Has anyone else noticed this issue? If you let the preview finish rendering before running the app, this doesn’t happen. Very odd.

Xcode Preview is not working. Successed to build Preview but error message displays like below: I think it's maybe related with loader path followed by error details below. I created xcproj file using tuist 4.19.0. How can I fix this issue? Error Details

I've recently started learning how to make IOS apps, but when trying to load the preview, it just shows the loading animation indefinitely. I am running xcode 15.2 (because my mac is a bit old and doesn't run the latest version) I have tried using version 15.1 but it still doesn't work, only works when I go down to version 14.3.1, but that changes the swift code.

I'm developing an app which supports for connect with an BLE device. There are some views for showing data from bluetooth. The code below for an example: @EnvironmentObject var bleManager: BLEManager // a class implemented CBCentralManagerDelegate var body: some View { // bleConnected is a CBPeripheral if let bleConnected = bleManager.bleConnected { if let services = bleConnected.services { ForEach(services, id:\.self) { service in // UI for print uuid, descriptions ... showServiceDescriptionView(services) if let characteristics = service.characteristics { ForEach(characteristics, id:\.self) { characteristic in // UI for print uuid, data for each characteristic showCharacteristicsDetailView(characteristic) } } } } } } } But it seems that Xcode Preview do not support connect to a real bluetooth device. So the preview window in Xcode will always be a empty view. I only can see the data on the real device. But it's important for me to design UI on the preview. So are there any method to mock a fake CBPeripheral in the Previewer? Or are there any other way to achieve this?

Hello everyone, I’m currently developing my first VisionOS app in Xcode, starting with the default "Hello World" code provided when creating a new VisionOS Mixed Reality App. However, I’m facing some issues with performance and previewing that I can’t seem to resolve. When I load the preview, it takes an extremely long time, and sometimes it doesn’t load at all. Even when I try to run the app in the VisionOS Simulator, the simulator shows an endless black screen and never displays the intended view. I’ve made no changes to the code, so it’s purely the base setup. Here are my system details: Xcode version: 16.1, VisionOs 2.0; macOS version: 15.0.1; Hardware: MacBook Air 2020 M1 I’ve tried restarting Xcode and my machine, but the issue persists. Has anyone else faced similar problems or have any suggestions for fixing this? Or is my hardware simply too weak? Any help would be greatly appreciated! Thank you in advance!

The simulator will not work. No matter How much I restart, when I open my app, it tells me either Build succeeded but I see a loading bar or a loading automatic phone simulator but it never shows up like the line would. keep going in a loop, for example this is what it looks like,

Hello, I recently decided to start learning how to code for iOS. I don't have much coding experience but I still wanted to explore it for fun at least. I downloaded Xcode on my Macbook, and opened a new iOS file after downloading iOS 18.1 so I could run the simulator/get a preview of my code. Even though I only had the basic "Hello World!" that is auto-generated in my code, the preview would never show and sat at a loading screen for multiple hours, saying "Preparing (Automatic) iPhone Simulator" at the top. There is probably a simple solution that I'm missing. I would appreciate any tips! Thanks.

I can't seem to access preview for any of my views in any of my swift projects at all (using Mac to code and using iPhone 16 pro as preview and simulation, simulation can work), even after restarting Mac and Xcode itself. The preview section has a popup saying "Cannot preview in this file, unexpected error occured" (for every file), please tell me what is wrong and help me solve it to see the preview, thank you! details

I'm trying to create a preview for my live activities when it's stale, so I created a preview provider. I followed some examples, but XCode says I'm missing preview context. Am I doing something wrong? I tried adding .previewContext(WidgetPreviewContext(family: .systemSmall)) but that doesn't seem to work.

Views can be viewed on the canvas in XCode via the code below. #Preview { ContentView() } But how do I preview an App class in XCode? Background: I'd like to preview various settings done in the Scene of the App.

I got a preview crash info as this: xxx crashed due to fatalError in PersistentModel.swift at line 559. This KeyPath does not appear to relate RecordInfo to anything - \RecordInfo.<computed 0x00000001921dfb4e (Array<SomeInfo>)> If I change preview device to iPhoneSE, It is no crash. I think the reason is I have some dirty data in iPhone16 Pro preview device. If I'm right and how to delete it? Model of RecordInfo like this: @Model class RecordInfo { @Relationship(deleteRule: .cascade) var someInfo:[SomeInfo] } @Model class SomeInfo { var date: Date var info: String }

My preview crashed because it could not access my font resources. I am working on a Framework, and it seems that for frameworks, the resources are not copied into the app package of the preview. Investigation: I verified this by examining the contents of the preview: /Users/YOUR_NAME/Library/Developer/Xcode/UserData/Previews/Simulator Devices/DEVICE_UUID/data/Containers/Bundle/Application/APPLICATION_UUID/APPLICATION_NAME.app Make sure to replace "YOUR_NAME," "DEVICE_UUID," "APPLICATION_UUID," and "APPLICATION_NAME" with the actual names or UUIDs relevant to your specific situation. Now right-click on the app and select Show Package Contents. For previews that work correctly, the name of the associated app is used, and you will see all the resources in the package. However, my framework was not using the framework name. Instead, it was named XCPreviewAgent.app and did not contain any resources from my framework. Fix: As of November 2024 (Xcode 16.0 and Xcode 16.1), the fix is to use Legacy Preview Execution. In the menu, select Editor > Canvas > Legacy Preview Execution. Please leave a comment if this is fixed in a newer Xcode version.